Smoothies are truly a wonderful creation. They are a quick, easy convenient way for you to add in all those awesome nutrients without the added preservatives and man made chemicals; you can add the ingredients that you love and leave out the ones you don't. Plus they taste so darn good!this is one of the great things about a smoothie - you have the freedom! While it definitely is best to take out the core of your apple or the hard seeds of your avocado, so you don't break the blades in your blender, the rest it up to you. You can peel your fruit/veges or leave the skin on for added fibre. It really is whatever tastes best for you!Yes, you can. But I would only suggest this with certain smoothies. Dairy can 'thicken' the longer it is left and the blended fruit/veges can oxidise and take on a brownish tinge. That being said, you can blend the fruit that night before and mix the dairy in the next day. Or, I find it easy to prepare what I want in my smoothie the night before and leave it in the fridge, all ready to throw into the blender in the morning!